The degree of the emission of CO2 from the incineration of fossil fuels into our atmosphere has manifested as one major reason for the global climate change. The effects of the climate change on earth initiated a global shift in the consciousness of mankind to utilize renewable energy sources instead of fossil fuels in order to reduce our CO2 emissions.
One major source of CO2 emitted into the atmosphere through fossil fuels is the generation of electric power. In order to curtail the CO2 emissions into our atmosphere quickly and effectively it is necessary to offer alternative electric energy generation systems utilizing renewable resources that are economically competitive compared to the systems using fossil fuels.
One way to generate electric energy through renewable resources is the conversion of biomass or other organic wastes into energy by pyrolyzation and the subsequent utilization of the pyrolysis gas through internal combustion machines or steam processes that drive generators to generate electricity. However, almost all the renewable energy sources suitable for the mentioned pyrolyzation process have in common the following: they do have a low energy density; they are locally dispersed. This creates the challenge faced to this technology to either have a centralized large pyrolysis plant where the organic material is transported to the plant from a large area; or to have decentralized small pyrolysis plants that are deployed in the area where the material is available to minimize the transportation. While the specific investment cost as well the highest degree of utilization of the energy of a pyrolysis system can be minimized by building centralized Plants with the highest possible capacity, the cost of the transportation of the feedstock increases since the material need to be sourced from farther away. Through the low energy density of the feedstock and the high transportation cost economical reasons prohibit the realization of such big centralized systems. Therefore there is a demand for smaller, decentralized pyrolysis units.
The disadvantage of these smaller pyrolysis units is the higher specific investment cost and lower energy efficiency. The challenge is to find a suitable technology for these decentralized units that is balanced between investment cost and efficiency. The pyrolysis of organic material contains many chemical reactions that produce, besides the readily utilizable gaseous products, unwanted byproducts, especially large complex hydrocarbons commonly known as soot and tars. These byproducts prohibit a direct utilization in an internal combustion machine because these byproducts cause early mechanical failure of the machine.
The prior art addresses these problems by e.g. direct combustion of the pyrolysis gas, and vapors with the subsequent utilization of the energy in a steam process. The disadvantage of a steam-only process is that a high energy efficiency of the process depends on the degree of utilization of the energy from the flue gas that needs to be transferred into the steam. To achieve this it is necessary to deploy large heat exchangers into the flue gas to generate high pressure steam that feeds multiple stage steam turbines. Therefore such systems are only economically sound when used in large-scale stationary power plants.
Another solution of the prior art is to eliminate the complex hydrocarbons during, or after the pyrolysis process by either condensing and filtering the unwanted byproducts or cracking the bonds of the large molecules with steam that is introduced into the pyrolysis reactor. The cleaned pyrolysis product is then directly used as fuel in internal combustion machines.
The prior art also addresses solutions to utilize the released heat by generating steam from the exhaust gases of the internal combustion machines. This steam then feeds a steam turbine that in turn generates electricity. This process, also commonly known as Combined Heat and Power (CHP) or Cogeneration, provides the highest degree of energy efficiency. Although CHP is very efficient, the relatively low exhaust gas temperatures released from the internal combustion machines require large and expensive heat exchangers.
All these aforementioned systems that generate and recover the energy from the pyrolysis product have in common that they are complex and need to be large to become economically feasible. But the larger the size and capacity of the aforementioned systems, the larger the radius of the area in which the organic material is gathered, grows. This increases the cost of transportation and makes such projects only in limited areas economically sound.
There is a need in the prior art for a system that provides all of the benefits of a mobile biomass pyrolyzation system with a high energy utilization rate and low specific investment cost.